#include <bits/stdc++.h>
#define PB push_back
#define MP make_pair
#define REP(i,n) for (int i=0;i<(n);i++)
#define FOR(i,a,b) for(int i=(a);i<(b);i++)
#define ALL(a) (a).begin(),(a).end()
using namespace std;
typedef long long ll;
typedef unsigned long long ull;
typedef pair<int,int> P;
const int INF=1e9;
const int MOD=100000;
int B=1000000;
int main(){
      int n,a[100000],ans=0;
      cin>>n;
      REP(i,n)cin>>a[i];
      sort(a,a+n);
      REP(i,n){
            if(i!=0)if(a[i]==a[i-1])continue;
            if(i!=n-1)if(a[i]==a[i+1])continue;
            ans++;
      }
      cout<<ans<<endl;
}